Baneberry
Operation Emery
Yield: 10 Kilotons
Location: Nevada Test Site
Date: December 18, 1970
Not all underground tests have successfully contained the radioactive products. In Baneberry, failure of the stemming and capping of the shaft allowed a radioactive jet to emerge. Radioactivity was detected off site (i.e. outside the Nevada Test Site). The release of 80 kilocuries of I-131 was by far the worst accidental release at NTS. This was an LLNL weapon related test.